1. Field of the Invention
The present invention pertains to flat cable and an apparatus for making flat cable. The invention more particularly concerns flat electrical cable with exposed conductors without adhesive residue and a modular rotary anvil which is used to manufacture the flat electrical cable.
2. Discussion of the Background
Flat electrical cables are well known in the art having conductors sandwiched between two insulating layers. Flat conductor cable is known in the art having an upper insulator layer having an adhesive adhered to a first side of the upper layer and a lower layer of insulating material having an adhesive adhered to a first side of the lower layer. A conductor or strands of conductors are placed between the upper and lower insulator layers and all three layers are secured together by the adhesive. However, use of adhesive to bond the layers is disadvantageous in that upon heating of the adhesive, the conductors may float in the free flowing adhesive causing the spacing between the conductors to be inconsistent and non-parallel. Upon drying and attempted attachment of the flat cable to a component, the improperly placed conductor may not align with the conductive leads of the component the cable is to be attached and, thus, the flat cable is unusable and must be discarded. Further, when the cable is stripped to expose the conductors for connection of the cable to a component, the conductors have an adhesive residue thereon which inhibits the conductive properties of the conductor. Also, if any scrap material of the insulator layers is produced, the scrap may not be recycled due to the presence of the adhesive on the insulator layer.
Other bonding techniques are known in the art for bonding multiple layers such as ultrasonic welding. Generally ultrasonic welding has been used for spot welding with thermoplastic materials using either a plunge mode or a shear mode. Therefore, the known methods of welding thermoplastic materials using ultrasonics did not provide for a continuous welded seam where the seam has great pull strength. In the area of electrical cables, seams of great pull strength are required and the previously known welding techniques are not sufficient.
The ultrasonic welding apparatus includes an ultrasonic welding machine 1, as shown in FIGS. 14 and 15. The ultrasonic welding machine 1 includes inner and outer brackets 2 and 3, the anvil frame 4, the horn 5, the pattern roller or rotary anvil 6 mounted to the anvil frame 4, a chain 7 to rotate the rotary anvil 6. However, other methods of rotating the rotary anvil 6 can be used. Socket head cap screws 8 attach the outer bracket 3 to the anvil frame 4. The rotary anvil 6 is mounted in opposition to the horn 5. As shown, in FIGS. 14 and 15, the work-piece (not shown) is fed into and through the gap 9 present between the horn 5 and the rotary anvil 6. As the horn 5 plunges or shears against the work-piece, the rotary anvil 6 remains rigid in the opposing direction of the force and subsequent impacting of the work-piece by the horn 5, thus reacting the forces generated by the process. In this example, as shown in FIGS. 14 and 15, the horn 5 does not rotate. As such, no pattern is formed on the side of the work-piece facing the horn 5, if the surface of the horn is flat and smooth. As the work-piece passes through the gap 9 between the horn 5 and the rotary anvil 6, the rotary anvil 6 rotates. Thus, a pattern can be imprinted on the surface of the work-piece. Such a method of manufacture requires that a unique anvil be created and inventoried for every type of and size of pattern desired to be formed on the work-piece.